Luminescent tube system and apparatus



P 1949- J. H. BRIDGES 2,481,468

LUM-INESCENT TUBE SYSTEM AND APPARATUS Original Filed Aug. 12, 1943 2Sheets-Sheet l V6 Samm Z X f I Sept. 6, 1949. J. H. BRIDGES 2,481,463

LUMINESCENT TUBE SYSTEM AND APPARATUS Originai Filed Aug. 12, 1943 2Sheets-Sheet 2 gluvucmlo o of my invention, while;

Patented Sept. 6, 1949 LUMINESCENT TUBE'SYSTEM AND APPARATUS I JohnHerold Bridges, New York, N. Y., assignor to National InventionsCorporation, a corporation of New Jersey 7 Original applicationAugustlZ, 1943, SeriabNo. 498,344. Divided and this application October1, 1946, Serial N0. 700,427 I Claims. (Cl. 315258) My application is adivision of my copending application 498,344 of August 12, 1943,entitled Luminescent tube system and apparatus, now patent 2,436,951 ofMarch 2, 1948, which in turn is a continuation-in-part of my copendingapplication Ser. No. 469,365 of December 1'7, 1942, entitled Luminescenttube system and apparatus, and the invention relates in general toelectric lighting systems and more especially concerns luminescent tubesystems of illumination and apparatus therein. A

The object of my invention is the provision of a safe, reliable andhighly practical gaseous electric discharge tube lighting systemincluding a transformer source of electrical energy. and a plurality oftubes, which system is characterized by thoroughly satisfactorydistribution of current to the tubes, by prompt and substantiallysimultaneous energization of the tubes, in which there is displayed butlittle'stroboscopic effect,

and which during operation has an exceedingly good power factor.

Another object of my invention is the provision of a gaseous electricdischarge tube lighting system including a single-transformer source ofelectrical supply, which system is especially adapted for operating fourup to as many as ten or more included light tubes, which achieves highlyeffective control over the tube-energizing current, and which is capableof continued operation in a safe and efficient manner despite failure ofone or more of the plurality of included tubes.

Other objects will in part be obvious and in part pointed outhereinafter in connection with the following description taken in thelight of the accompanying drawing,

In the accompanying drawing:

Figure 1 represents a gaseous electric discharge v tube lighting systemincluding certain features Figure 2 is a diagram of the circuit employedin Figure 1 and additionally illustrates an advantageous grouping oftubes, and;

Figure 3 depicts a modified form of system in accordance with myinvention.

As conducive to a clearer understanding of certain features of myinvention, it may be noted at this point that gaseous electric dischargetube lighting systems are today in wide acceptance in various fields ofillumination where incandescent lighting systems formerly were employed.There are numerous advantages which more than justify the employment ofsuch lighting systems,

among these being characteristically low power consumption, coolness ofoperation, simplicity, sturdiness, improved dissemination of light,'andwide choice in the physical form of tube or tubes employed. A number ofdifferent physical dispositions or arrangements, moreover are possiblein obtaining desired lighting effects as in factories, stores, andprivate homes ;-and the use of a variety of fillings such as fluorescentsalts on phosphorus as active ingredients of the tubes enables theprovision of a number of different colors of light. 1

Although," as pointed out, there has been wide acceptance of gaseouselectric discharge. tube lighting, many of the systems present featureswhich for practical reasons are'not wholly 'desirable:- Certain of thesystems. essentially operate at low voltages and the tubesrequirepreheating before initial starting is successfully achieved.These systems usually include a heater circuit and switchovermechanismwhich, as appurtenances, represent items of expense and asource of possible trouble in operation. A further objection 1 exists inthat the tubes flicker during the preheating periodand considerabledelay occurs before steady operation is achieved. Hot cathode tubesystems also are found to be unstable in operation at low temperatures,such as under temperature conditions frequently encountered in outdooruse.

In certain heretofore known gaseous electric discharge tube systems ofthe multi-tube type, failure of one or more of the included tubesdisrupts further operation until full and proper replacement of the wornout tubes is made. This latter objection is notable particularly inlighting systems which include a single transformer source of power anda plurality of tubes connected in series with each other and with thesource of power. Such'systems-also require an increase in operatingpotential where the number; sizegor length of tubes is increased. On theother hand an upper limit on voltages is imposed by the FireUnderwriters'and thus the number of tubes employed as well as thedimensions thereof are sharply curtailed.

There too, are multi-tube systems wherein the tubes are connected inparallel across a source of electrical supply. In these systems loweroperating potentials are made possible than should series connection oftubes be employed. There is, however, a tendency in such systems for anincluded tube of low starting potential or of high conductance to drawsuch a large part of the load current available that other includedtubes either fail to start, or when they do start, draw such lowcurrents that the current densities are wholly in- 3 V sufiicient toproduce the desired brilliant glow. Still another objectionable feature,commonly termed stroboscopic efiect, is encountered in gas- 7 eyes, verydiscomforting, and in all is wholly desirable.

One of the outstanding objectsof' my ii iveii'ifion', Hi6

accordingly, is the provisionof a system if il mmr nation including aplurality of gaseous electric discharge tubes and a singletransformer-source of electrical supply, in which system continuousoperation of the tubes is notdisruptd by ,failureof one or several ofthe tuhes,l. in;which;all ftnbes promptly reach substantially fullconductance r and brilliance and give a stable quality of illuminationin and after starting, and in whioh a maximum length of tubing is safelyand efliciently ape-rated. r

'sRei erring now :to the :general zipractiee {of invention, .1 provide.:an electrical illuminating system which comprises a step-suptransiiurmer, and :a plurality of gaseous ieleutric discharge tubes,advantageously eight to tender :or seven 'a's'ifiew as :fzoln :tubesindividually I'conneeted ii-n maraliel with :a single :outpnit source ofthe "transformer. Each stuhe :cirmiitiiinclndes tan rz-imluctiue*reactance, and a gaseous electric discharge tube connected in series.'oneznrim'one or Ithe'Jmbe icircuits, suchras alternatecir'ouits..-additionally include a, condenser conrrectecl in the tube andiin'ductiue reactance. Eline inductive neactances tnrefierahlyia'reofrgsnch l typelas more fully :pointcd out-hereinafter;

illustratiue-iof the of any invention {in 11 :of the dnawmg thereelectric lighting system :con inrising ta shellatywe .step npitransrormm' in! having an imiernmieiportron I51 flanked on :oppositesidesebyl :C shaped V imiter dore' portions -12 .and its. 'Ilhetransformer core ima'de f paramagnetic material zsuch -;as or laminatediron. The zinnerpoitioniotfi'the owe mfera'bly has a6ross-sectiona1learea subshan finally itwice' as iarge either mimeiouter more iportions.

Inia'ss'embled condition thednansifomner none V maths mutually including.ilnrner oore'portioniil-li and respectively including outer moreipjortionsjwlsz and .:It will, L-hOW (IVBT FbE umderstood that-ideaspirecertain aclya'n'tages being achieved through :the use @of a ,shell typetransformer, a care w xtr ans former may instead be employed-in my.

'rl ig htingsystem. 1' V The :transfiomner shown includes la.

:ooil d4 'wvound tor ;example of heavy gauge wine V and disposed about:iin-ner aOOIB portion 114,. Sunjply ileads 46 fand ll extend :fromia-nalternating @curnent :source of electrical supply 158,.nonyendentlysoflw and 220 voltsrating toeppositeiends :01 thevtransformer primary coil .;A secondary coil l5 also disposed aboutinner coregportion Elli adjacent the l-primary (coil preferabl is woundnof small gauge wire and possesses .such number of turns as to haveinduced therein :ajdesined gstepped-up ,output voltage. At times .,Imount the" rprimary and secondary coils -.on .the transformer core .insuperimposed rre'lationship so as so ,gain maximum advantage ofcompactness and isa ifings in materials. j M :While-it is within theprovince of my inven- ;tion to employ the transformer Ll]! .as anror'difnary ltransformer with the primary and ,sec-

ondary windings related only inductively, I prefer to produce thenecessary high output voltages by means of autotransformer connection. 7Thus,

- 'ner :co're port'ion l l linking secondary coil l5 qretinningthroughouter core portions l2 and I*3to the primary winding. A high terminalvoltage, zalccordingly, is induced in the transformer 2Q secondarywinding, which winding for autotransiormer ,connection consists of lthesenies con-r nected coils l hand l5. 7 r .In .rthe ensuing half-cycle of{primary current the direction rof current is reviersediand fluxcoursestrom the ,primary windingsthrough inner co'reportion .Llto theleft Eigure;1.- l'lhediiux,

in returning to V the primary {winding courses to the right along routercore portions ill-and l3 -and tqlthe left back through inner coreportion LL, The coils]; and \L5Lagainare linkedlimgne'tically'andlanelectromotive forcenfnpposite direction ,to, that resulting from thefirst-half cycle of primary current-builds rupgacross the transformerseccndaryawinding. I 35, In. the illustrative embodiment o'f ,my viruen- V ltion I shown injEigure 1,, I emplo some eight;to 'ten' or "more,'{or as few ,as lfour fluorescent gas .d ischangetubesl; such .asfltubes' :Iil, T2, 113;,14, etcpgviconnected in parallel acnoss theautotransifonmer windings .of' transtormer Ill .One of the parallel tubecircuits conveniently is traced the righthand side of secondarycoil 1L5worked 22 to .terminal123; thence ,overleads 25 rand'zli, "through tubeialqng lead 721, Winding 'W,l -,of

mreacftur .Rl.,,and lead 28 over lead 2] .toi-terinitial 210; and thenceelonglead 1.6,, across coil 11., lead [9 and coil 15 lbaok to the mintrbe innin the ri hthand side of secondary ,coil I5 ouerIlead V 2,2 .toterminal 23,; lead condenser .Cw and 'lead 29 toitube T2, thron -h tubev.over lead 310, and across windingWl of'reac'tor R2; overleads .3 I.and 2] to terminalzq; and thence'alon-g lead Z5,.,.acro#ss Qoi1'. |'4,,,lead1%,.ahd coil l5 back-tattle ,point of beginning. j

Tube T3 is energized inn .circuittitaqed from the righthand .side' ofcoil 15.0w! lead 22 to terminal 23,; thence lover leads .25 and 32,through tube across lead 33,, windingW3 ..of reactor R3, and lead'3'4;along leadfl] lto iterm'inal 2 and across lead 1.6. can 1.4, deadL'S'andcoil "l5'bagfiki0fihefi0inhof beginning. r

Another tube circuit, beg nning .at the ri ht 5 handend .of coil ll 5',extends over lead .22., through terminal '23 across lead i2 ,,vcondenserC, and

7 actors may .be connectedlacross .lea'dsQZJ and 124 7 ,so .as to .Iormparallel .condensiye circuits with Y the tran former, nutput winding,and/prim in the present embodiment of my invention, I 7

Assume, for

TA second tube circuit "is'traced' beginning =,at

parallel across leads 2I and 25 so as not td include the condenser C.The tubes of the entire system provided advantageously are grouped orbanked such as in pairs of adjacent or contiguous tubes with one tubeonly of each pair being in a condensive circuit. Other groupings may beused in which at least one tube in condensive circuit is present, evento the extent of all the tubes of the system being in one bank. Eachtube circuit may be closed by a separate switch (not shown) or each bankmay be controlled through a separate switch, as pointed out moreparticularly hereinafter with respect to the embodiment illustrated inFigure 3. Where the-tubes of the entire system form but one bank, I findadvantage in placing alternate tubes in condensive circuits andcontrolling pairs of adjacent tubes with corresponding switches.

Through the use of a reactor in each oithe tube circuits, any tendencyfor one circuit to draw such high currents that the current density inthe remaining circuits is insufiicient to produce light at-fullbrilliance, is substantially dispelled. The additional use of acondenser in several of the tube circuits lends an improved power factorto the entire lighting system. Tubes in the condensive circuits,moreover, operate in out of phase relationship with the tubes in theremaining circuits so as to maintain stroboscopic effect of lightemitted from the system as a whole at a minimum. l

The lighting system is highly efiicient in operation and has particularutility where some eight or ten or more gaseous electric dischargetubes, or even as few as four of such tubes, of substantial length, areto be energized. The tubes employed are found to have long life due at'least partially to the excellent control over energizing currentmaintained in the system. With an increased number of tubes in thesystem, initial installation costs are readily justified, especiallyWhen account is given to cost of installing and maintaining a likenumber of tubes in accordance with the prior art. By operating onincreased number of tubes with a single transformer, as for example, upto '70 inches or more of 25 millimeter tubing, core losses in the systemdecreases, and operational efiiciency increases all the more. Thecharacteristic reduction in stroboscopic effect achieved is enjoyed atfull maximum by grouping the tubes so as to obtain blended light fromthe tubes operating in diiferent phase relationship. One advantageousgrouping of tubes is shown diagrammati cally in Figure 2 of the drawingwhere-paired tubes in adjacent side by side relationship are connectedas in Figure 1 for out of phase operation.

I prefer to use reactors in my lighting system which display little, ifany, current controlling action when no-load conditions prevail, butwhich instantly interpose high reactances when the tube loads areenergized and high current begins to flow.

A reactor, illustrative of the type just mentioned, is indicatedgenerally in Figure 1 by reference character RI. The embodiment shownincludes a shell-type core comprising a longitudinal inner core portion38 having a reactor winding W I thereon and terminating at one end inoppositely extending transverse portions El, E2. Outer core portions 39and 40 extend from the other end of inner core portion 38 around windingWI to points just short of the ends of extensions EI, E2, respectively.The outer core 'portions thus form magnetic paths through andreluctance.I prefer to make core portions 33 and 40 of like cross-section and theinner core portion approximately twice as large in cross section aseither of the outer core portions. I also prefer to maintain asymmetrical disposi-- tion of all component core legs in the reactorassembly and equal calibration of air-gaps so as to obtain balancedmagnetic conditions in the several magneticpaths of the reactor.

Similarly, reactors R2, R3 and R4 comprise inner core portions 38a, 38band 380, respective-- ly, and corresponding laterally extending endportions E3, E4; E5, E6; and E1, E8. Reactor windingsW2, W3, W4 aremounted on respective inner core portions of the reactors. Outer coreportions 3311,4011; 39b, 40b; 39c, 40c extending from opposite sides'ofthe lefthand ends'of the inner core portions, form air-gaps G3, G4; G5,G6, G1, G8 of calibrated reluctance with the laterally extending endportions.

In the present embodiment the reactors RIR.4 are designed for the sameor similar tube loads, and one substantially alike in construction. Itwill be understood, however, that the reactors may possess differentcurrent limiting qualities depending, for example, upon the tube loadsto be energized in the individual parallel circuits. The reactors alsomay to good advantage be of the core-type having single magneticcircuits interrupted by fan included air-gap of calibrated reluctance.

When the primary circuit of transformer I0, including alternatingcurrent source'of supply I8, lead I6, primary winding I4 and lead I1, isclosed by means of a suitable switch (not shown) an induced voltage isimpressed across the transformer output terminals 20, 23. This Voltagerises and falls at the same rate as does the current through the primarywinding I4 and a tendency exists to develop a flux in the magnetic pathsor circuits of the reactor cores. The direction of this flux is such asto induce in the coils WI, W2, W3 and W4 by self-inductance a voltagetending tooppose the provision of the included air-gaps GIG8 in thereactor cores the decrease in secondary voltage could reach importantvalues and could appreciably retard the initial energization of thetubes. It is to nullify the effect of the self-induced voltage that theair-gaps 'GI-G8 are provided.

The tubes thus are energized readily, and a high current tends to flowthrough the system able quantity. A voltage, proportionate to theincreased current, is induced in coils W IW4 to oppose further increasein current through the coils and to limit current flow through the tubesTI-T6.

It will, therefore, be seen that the reactors not only permitsubstantially full terminal voltage to be impressed across thecorresponding tube loads at the time of starting, but seem to counteractthe tendency for increasein current flow due to negative resistancecharacteristics of the tube loads or due to short-ci'rcuiting. Theair-gaps in the reactor "magnetic circuits, 1 being of such arena 7Fealibrated reluctance as to'prevent a. substantial amount of no-loadflux from passing .thereacross and yet not being oflsuch high reluctanceas to prevent .an appreciable amount of flux from crossing while thetubes are energized, are instru- 1 mental in maintaining thetube-energizing current within safe and properly controlled limitswithout impairment of the rapid starting characteristics of the tubes.

In Figure 3 of the drawing a somewhat-moth fled lighting system inaccordance :with any invention is illustrated. The system isparticularly "useful where a plurality of light sources controlled byseparate switches areneeded as in auditorium or stage lighting or inilluminatinga number ofroom's of a building. Astep-u trans- :former All,such as an autotransformer having a primary winding 45 and a-secondarywindin vinclucling coils 45 and'46,is employed for'energizi-ngsome-eight to tenor more or even as few'as four gaseous electricdischarge tubes, illustratively tubes T5--Tl0, connected in parallelwith the transformer secondary winding. :The tubes preferably arearranged in'remotely spaced-or contiguous banks, each bank comprisingtwo or more tubes, such as tubes T5-,-T6, v 'I"i-.T8, and T TH), isprovidedwith an energizin circuit which includes condenser and reactormeans; and at" least oneother tube, as one of tubes 'lfi, T'Land T9 iscontrolled :by reactor means without the and light emittedfrom theenergized is 'rthe "tubes display long life and thoroughly satis--factorylig'ht-emissive qualities. 7 I; also prefer to employ tubeslined with a fluorescentcoatingof phosphor and filled with a gas such asneon, ar-' gon, helium, or the-like, with or ithout mercury Va pOI'w Inmy lighting system the particular parallel network .distributes'higheroperating voltages for 7 given output voltage than doesthe conventionalseries connection heretofore'employed. The tubes strike extremelyrapidly. and give off a steady light during operation even Where coldweather conditions prevail. I find'that in using a high secondaryterminal voltage of, for example, :550

aid of a condenser. The tubesin each bank ad- 7 vantageousl are groupedtogether as inside vby side relationship illus'trativelyin a fixturehaving a suitable reflector,land are controlled by switch means, as foreXample-oneof the switches 48, '52 or. 56, independently of tubes in theother banks. v

In the embodimental systemillustratedin Figure 3, a secondary circuitmay bevtracedfrom the righthand side of coil 46 over leads 4'! and 48including switch 43a; lead 49 through reactorRE, lead a, tube T5 andleads 5| 44 to junction 43, and thence along lead 43' throughautotransformer cells 45 and 46 back to the point or beginning. Aparallel circuit is traced from the righthand side :of coil 46 acrossleads 4'! and ,48 includin switch 48a, lead 50, reactor RileadEllafthrough tube T6 and over lead v511b, through V condenser C5; leads50c, 5| and 44 to junction 43, and along lead 4| and throughcoilsdli an45 back to the point of beginning.

Likewise, parallel circuits are closed across the transformer outputline Hill through lead 52 including switch 52a, first along lead 53,through reactor RLlead 53a, across tube T1 and through lead 531) andlead and, secondly, along lead 54b, through condenser C8 and acrossleads 54c and 55.

Similarly, two other parallel through lead 56, includin switch 55a,across lead 5'! and reactor R9, thence over lead 51a and through tubeT9, and over leads 51b and 59; and; secondly, by Way of lead 56including switch 56a,

lead '58 and reactor Rio, thence acrosslead 55a and tube T10, along lead58b through condenser CW, and leads 58c and 59, respectively or 600Volts, 'whichstill is Within the limits permitted by theFireUnderwriters for .autotransformer equipment, a: maximum length of isquite successfully energized. V I "Thus it will be seen that with myinvention there is provided asystem of illumination in which the objectshereinbefor'e noted, together with many-thoroughly practicaladvantages/are successfully achieved. It will be seen that a.

single transformer output source is used insu-pe circuits areclosedacross the transformer output leads 44, 41, first system, comprising incombination; a trainsformer including a primary winding connected -Whilethe tubes in the several parallel circuits may be energized from thetransformer secondary winding through individual switches in each en- 11 ergi-z-ing circuit, particular advantage is gained by energizing thetubes in banks including out of ,phase tubes through a switchecorresponding to each bank as a whole. Thus when a particular switchisclosed, outof phase operationiis plying energizing current' to' aplurality of gaseous Zelectric discharge tubes in several parallelcircuits, and that the voltage in the several circuits is'notonlyhigh'but of substantially uniform value. It, will further be seen thatthe particular choke-condenser principles employed lend to promptenergization of the tubes, a

" steady character of illumination substantially free of stroboscopic'effect Where the tubes are closely grouped as hereinbefore described,and a hi hlysatis'factory power factor; and that the system .is adaptedfor operating a maximum length of included tubing and capableof safe,

continued operation despitethe failure of one :01

more of the several tubes.

r As manyvpossible embodiments may .be made of my invention and as manychanges may be made the embodiments hereinbefore set forth, it

will be understood that all matter described herein or "shown in theaccompanying drawing ,is to be interpreted as illustrative, and not in alimitingsense. f r .7 f

['I claim: r -i' r a '1. A gaseous-electric dischargetube lightingacross a source of electrical supply, and a secondary winding step-upsource of output supply; 7 at least two pairs of gaseouselectricdischargze tubes connected .in.parallel1acircuits with saidtransformer secondary winding; current Elihu-ting iselfinductanceshaving magnetic cores :and :included air-gaps included in each circuitof each 1 :pair of said parallel circuits; and individual condensersadditionally included fin one of each pair ,of said circuits foreiT-ecting dizfiierzent phase operation for one tube cincuitrofeachspatrtubing 7 as compared with the remaining tube circuit of that pair,

2. A gaseous-electric discharge tube lighting system, comprising incombination; a transformer having an electrically continuous secondarywinding; a plurality of tube banks individually including two gaseouselectric discharge tubes; current limiting self-inductances havingmagnetic cores and included air-gaps included in circuit with each ofthe tubes; and individual condensers additionally included in circuitwith one tube of each bank for effecting different phase operation forone tube of each bank as compared with another tube in the bank.

3. A gaseous-electric discharge tube lighting system, comprising incombination; a transformer having a secondary winding; two pairs ofgaseous electric discharge tubes connected in parallel with saidsecondary winding and energized by said secondary winding throughswitches corresponding to the pairs; current-limiting selfinductanceshaving magnetic cores with included air-gaps included in circuit witheach of the tube circuits; and a condenser included in one tube circuitof each pair of tubes for reducing stroboscopic efiect.

4. A gaseous electric discharge tube lighting system, comprising incombination; a transformer having a shell-type core with a primarywinding mounted on the central leg thereof and adapted to be connectedacross a source of supply, and a secondary winding also mounted on saidcentral core leg; a pair of gaseous electric discharge tubes connectedin parallel circuits with said transformer secondary winding; twocurrent limiting self-inductances having magnetic cores and includedair-gaps respectively connected in said parallel circuits; and anelectrical condenser additionally included in one of said circuits foreffecting different phase operation for one tube circuit as comparedwith the other tube circuit.

5. A gaseous electric discharge tube lighting system, comprising incombination; a transformer having a shell-type core with a primarywinding mounted on the central leg thereof and adapted to be connectedacross a source of electrical supply, and a secondary winding alsomounted on the central leg of said core and connected inauto-transformer relation with said primary winding; a pair of gaseouselectric discharge tubes connected in parallel circuits with saidtransformer primary and secondary windings; two current limitingself-inductances having shell-type cores with included air-gapsrespectively connected in said parallel circuits; and an electricalcondenser additionally included in one of said circuits for effectingdifferent phase operation for one tube circuit as compared with theother tube circuit.

JOHN HEROLD BRIDGES.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,050,135 Tour Aug. 4, 19362,298,935 Freeman Oct. 13, 1942

